Unfoamed polyether urethane,nitramine bonded high explosive



United States Patent 3,507,722 Patented Apr. 21, 1970 used explosive which melts at 177.62 F. However, RDX 3,507,722 which melts and decomposes at 399.2 F. and HMX which UNFOAMED POLYETHER URETHANE, NITRA- MINE BONDED HIGH EXPLOSIVE Joseph T. Hamrick, Roanoke County, Va.

melts and decomposes at 536 F. are too sliock sensitive for use in the pure state in bombs or other ordnance devices (6364 J valley Road SE Roanoke, 24014) 5 and must be mixed with less shock sensitive or shock in- No Drawing. Continuation-impart of application Ser. No. sensitive materials. The greater the amount of shock in- 542,432, Apr. 12, 1966. This application Aug. 9, 1967, sensitive materials the lower the shock sensitivity of the Cl C06! 15/02 explosive. Tests have shown that the specimens below Cl. 149 19 2 Claims when subjected to the shock of a U.S. Army Corps of 10 Engineers special blasting cap J-2 did not detonate in 2 trials. The specimen can be detonated with a 160 gram ABSTRACT OF THE DISCLOSURE charge of pentaerythritol tetranitrate more commonly known as PETN.

ThlS invention consists of a high explosive system comprising a flexible unfoamed polyether urethane binder and polyeiher Prepobfmer whlch the glam binder RDX (or HMX) alone or with atomized aluminum. The constitutent is mixed with the other ingredients before TABLE I Percent of mix D t t 8 3 Polyether Aluminum Specimen (imb e dd ti urethane 120 atomized size and Specimen in center RDX rubber powder shape temp., F of cube) Effect on specimen 70 30 2 in. cube--- 60 .T-2 Specimen broke apart. Did

not detonate. 65 10 do 60 .T-2 Do. 67 2s 5 .imdo 60 J-2 Do.

explosive is cast and cured in an armament case adhering adding a curing agent. Preparation of the prepolymer is tightly to the case, reinforcing it and forming a tough, as follows: water resistant, and heat resistant (350 F.) explosive with Mix under a nitrogen atmosphere 46 parts of 2000 molow impact sensitivity. It can be cycled from 65 F. to lecular weight polypropylene glycol and 31 parts of 3000 350 F. without cracking or separating from the armamolecular weight propylene oxide adduct of 1,2,6-hexanement case. triol and hold at 150 F. until both components are liquid. Add 18.4 parts of 2,4-toluene diisocyanate; and 4.6 parts This application is a continuation in part of my copend of 2,6-tolylenedisocyanate by means of a dropping fur nel. ing application Ser. No. 542,432 filed Apr. 12, 1966, now 35 9 heatmg F reactlo tealperature P 212 abandoned is reached. Hold this temperature until a viscosity of 5000 This invention relates to the manufacture of high ex- P. at 770 is t The quanflty of tolylene plosive compositions. More particularly it relates to a duspcyanate lsomer mm can be vaned to amve at the method of binding together explosive particles of RDX optlmum N i A 5 Per.cent i has been (cyclOtfimethylenetrinitramine) or HMX (Cyc1otetm found satisfactory in the sub ect application. The 5000 methylenetetrani'tramine) alone or with atomized alumolecular Welght propylene adducfls of glycerm or minum powder. The binding material is an unfoamed polyminethylolpmpane may be m Place of the Q P F ether urethane rubber The specific gravity of the explosive oxide adduct of 1,2,6-hexanetri01 with some variations in is approximately L6. physical properties. Some variations in preparation of the It is the primary object of this invention to provide an above polyether urethane prepolylner can of i be explosive system which when poured and cured in a mold tolerated. Therefore, the preparation process is intended or military armament case forms a flexible, tough, and to be represeritatwe and not m moisture resistant high explosive which adheres to the The fqnoWmg examples are lllusmitlve of my mventlon armament case and which can be cycled over a temperaand Wlth the i i f they are Intended to be repre' ture range from 65 F. to 350 F. without cracking, sentanve and not hmltmg' melting, or separating from the case. In the case of [HMX EXAMPLE I filled explosive, the upper limit is approximately 400 F. An additional objective is to provide an explosive mixture Z g3E g g gg ggg g gigs; a which not only can be cast and cured in the armament case d h 5 1 1 f but which will adhere tightly to and reinforce the armaan mlx mm omogenefms' 5.parts 0 m0 ten imethylolpropane and mix until the trimeth 101 ro ane 1s ment case. Examples of this requirement are armaments y p p which are designed to penetrate hard surfaces before ex- 7 dlstnbilteii but not more. than approxlmately Y Ploding m nutes. Mix in a vacuum mixer or evacuate the mix Tests have shown that the shear strength at the interface gg af i i i life of between the explosive and case exceeds 900 pounds per pour lmme m e y m o t 6 mo S .coate m- Square inch or bonded surface The explosive of this ternally with a release agent such as Teflon or into armavention when poured and cured to a solid tough composiment 2 not i g release agent 3 68 2 2 cases ure in t e mo or armament case at or ents use in ma e ex osive must e e twater ree. od for which it will withstand this treatment in excess of g p p 180 days was not determined. RDX (or HMX) without additives has 1.5 times the explosive power of 2,4,6-trinitrotoluene, more commonly known as TNT, a commonly EXAMPLE 11 Place 17.17 parts of the polyether prepolymer in a mixing bowl held at 200 F. Add 23 parts of finely atomized aluminum powder and 59 parts of RDX (or HMX) and mix until homogeneous. Add .83 part of molten trimethylolpropane and mix until the trimethylolpropane is well distributed but not more than approximately minutes. From this point the procedure is thesame as that for Example I.

In both samples the curing agent trimethylolpropane can be replaced by other polyols such as a mixture of trimethylolpropane and 1,4-butanediol, or amines. These may cause variations in the time before the mixture is too thick to pour (pot life). A mixture of .9 part of trimethylolpropane and 3.2 parts of 1,4-butanediol per hundred is approximately equal in effect to 4.7 parts of trimethylolpropane per hundred. Most amines result in too short a pot life to allow casting. Three eighth inch cubes of RDX explosives made by the process of Examples I and II were heated to a temperature of 350 F. for one hour without melting. A 5 inch by 5 inch X 2.8 inch block of RDX exlosive made by the process of Example II was cycled from -65 F. to 180 F. over a 24 hour period (16 hours at 65 F. and 8 hours at 180 F.) 30 times Without any evidence of cracking or other physical deterioration. Because of the greater flexibility at higher temperatures, it was not considered necessary to cycle higher than 4 180 F. to show the capability of cycling to 350 F. in view of the results with the inch cubes.

I claim as my invention:

1. A castable explosive system comprising approximately 15 to weight percent of unfoamed polyether urethane rubber and 50 to weight percent of cyclotrirnethylenetrinitramine or cyclotetramethylenetetraniti'amine.

2. A castable explosive system of claim 1 in which atomized aluminum particles in the amount of 5 to 35 percent are substituted for equal weight percents of RDX or HMX.

References Cited UNITED STATES PATENTS 2,845,025 7/1958 Stark 14992 X 3,147,162 9/1964 Paul 14919 3,269,880 8/1966 Visnov et a1. 149-92 X 3,350,245 10/1967 Dickinson 149-19 BENJAMIN R. PADGETT, Primary Examiner U.S. Cl. X.R. 149--92, 109 

